Novel haunch reinforcement for primay composite beams

The use of haunches in composite beams can result in a reduction in stud connector strength below that for a solid slab depending on the width of the haunch, the geometry of the profile shape, the sheeting thickness, the sheeting continuity, the number of studs at a cross-section and the proximity of the studs to the sheeting webs. The results of recent research and testing are presented that show that the strength reductions can be significant and can be more severe than predicted by design codes. Moreover, brittle failure modes have been observed involving longitudinal and diagonal splitting in the haunch region, concrete pull-out, and delamination of the concrete slab from the haunch. Two novel types of ladder reinforcing conponents, one including handlebars, have been developed to prevent these failure modes, resulting in significantly increased stud strengths and ductility.